In sheet handling industries, especially in the manufacture of corrugated paper cartons or boxes, large rectangular corrugated sheet blanks are stacked for storage and handling purposes. They are subsequently processed from the large upright stacks through various apparatus such as printers, die cutters, etc. according to customer requirements. Forming and printing type machinery often function at high speed. Thus, bulk quantities of stacked sheet material must be adequately fed to such machinery in order to maximize efficiency. The capacities of the handling apparatus are such that manual labor is not at all feasible. Automatic, mechanical machinery is therefore required to infeed the sheet material at adequate rates.
Stacks of sheet material are handled often in discrete quantities or "blocks" which are comprised of small numbers of the stacked sheets. Such "blocks" are more easily handled than large stacks.
Machinery has been developed to divide the large sheet material stacks into successive blocks for further handling. Block forming has been accomplished mechanically with only reasonable success.
A fairly typical problem accompanying the block formation process is that of "trailing sheets". Because of the many variations that can occur in production of the sheet material, as well as frictional and static electricity forces that can interfere with separation of a stack, sliding successive blocks of sheets from the top of a stack often results in a trailing sheet, usually the next top sheet of the stack, being dragged partially across the stack under the removed block. The protruding edges of the trailing sheet can subsequently jam the downstream machinery and thereby cause undesirable down time.
The present apparatus is intended to eliminate trailing sheets by keeping such sheets in position on the stack as successive blocks of sheets are removed therefrom.
The present apparatus resolves the trailing sheet problem by applying a friction surface against the next successive prescribed sheet under each successive block, and by frictionally holding the prescribed sheet in place as the above block is moved laterally of the stack. The prescribed sheet is held securely against "trailing" with the moving block as the block is engaged and moved horizontally from the stack.